Amethyst is macrocrystalline quartz in colors ranging from green to pale lilac and deep reddish purple. Rose de France amethyst is a popular trade name for a very light-violet colored amethyst, while a deeper fine rich purple color variety of amethyst is often referred to as Siberian amethyst.
Usually a specific locality is often associated with such trade names because of a reputation earned for producing the best of quality (Pariaba Tourmaline, Kashmir sapphire, Pailin Saphire and etc), but in the case of Siberian Amethyst and Rose de France Amethyst, this is not the case as most of the finest quality amethyst available today is sourced from Brazil, as well as Ceylon (Sri Lanka).
Amethyst can be transparent to translucent and many different shapes and sizes, either faceted or cut en cabochon. Value per carat in amethyst, unlike many gems, doesn't rise exponentially with weight as it is readily available in large sizes; but depends almost entirely on color. The "Siberian" deep purple with red and blue flashes commands the highest prices.
Green amethyst, new to the market, is produced by heat treatment. Purple amethyst cabochons are great for statement jewelry pieces, such as large pendants and rings because they are available in large sizes. Amethyst is the February birthstone and the birthstone for those born under the sign of Pisces. Amethyst is believed to be a stone of sobriety.